Rollup merge of rust-lang#143880 - Enselic:fn-parameters-on-different-lines-debuginfo, r=Mark-Simulacrum

tests: Test line debuginfo for linebreaked function parameters

Closes rust-lang#45010 which just [E-needs-test](rust-lang#45010 (comment)).

To verify that this is actually a regression test, do this, which is a simplified and adapted version of what compiletest does for 1.39 and then 1.88:

```sh
for toolchain in 1.39 1.88; do
    echo -e "\nWith $toolchain:"
    rustc +$toolchain "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--emit" "llvm-ir" "-o" "/tmp/fn-parameters-on-different-lines-debuginfo.ll"  "-g" "-Copt-level=0"
    "build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" "--input-file" "/tmp/fn-parameters-on-different-lines-debuginfo.ll" "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--check-prefix=CHECK" "--dump-input-context" "100" && echo OK || echo FAIL
done
```

which gives

```
With 1.39:
FAIL

With 1.88:
OK
```

<details>
<summary>Click to expand full output</summary>

```
$ for toolchain in 1.39 1.88; do
    echo -e "\nWith $toolchain:"
    rustc +$toolchain "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--emit" "llvm-ir" "-o" "/tmp/fn-parameters-on-different-lines-debuginfo.ll"  "-g" "-Copt-level=0"
    "build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" "--input-file" "/tmp/fn-parameters-on-different-lines-debuginfo.ll" "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--check-prefix=CHECK" "--dump-input-context" "100" && echo OK || echo FAIL
done

With 1.39:
tests/codegen/fn-parameters-on-different-lines-debuginfo.rs:16:16: error: CHECK-SAME: expected string not found in input
// CHECK-SAME: line: 10
               ^
/tmp/fn-parameters-on-different-lines-debuginfo.ll:69:42: note: scanning from here
!10 = !DILocalVariable(name: "x", arg: 1, scope: !5, file: !3, line: 1, type: !9)
                                         ^
/tmp/fn-parameters-on-different-lines-debuginfo.ll:69:64: note: possible intended match here
!10 = !DILocalVariable(name: "x", arg: 1, scope: !5, file: !3, line: 1, type: !9)
                                                               ^

Input file: /tmp/fn-parameters-on-different-lines-debuginfo.ll
Check file: tests/codegen/fn-parameters-on-different-lines-debuginfo.rs

-dump-input=help explains the following input dump.

Input was:
<<<<<<
           1: ; ModuleID = 'fn_parameters_on_different_lines_debuginfo.3a1fbbbh-cgu.0'
           2: source_filename = "fn_parameters_on_different_lines_debuginfo.3a1fbbbh-cgu.0"
           3: target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
           4: target triple = "x86_64-unknown-linux-gnu"
           5:
           6: `@str.0` = internal constant [59 x i8] c"tests/codegen/fn-parameters-on-different-lines-debuginfo.rs"
           7: `@str.1` = internal constant [28 x i8] c"attempt to add with overflow"
           8: `@panic_loc.2` = private unnamed_addr constant { { [0 x i8]*, i64 }, { [0 x i8]*, i64 }, i32, i32 } { { [0 x i8]*, i64 } { [0 x i8]* bitcast ([28 x i8]* `@str.1` to [0 x i8]*), i64 28 }, { [0 x i8]*, i64 } { [0 x i8]* bitcast ([59 x i8]* `@str.0` to [0 x i8]*), i64 59 }, i32 13, i32 3 }, align 8
           9: `@__rustc_debug_gdb_scripts_section__` = linkonce_odr unnamed_addr constant [34 x i8] c"\01gdb_load_rust_pretty_printers.py\00", section ".debug_gdb_scripts", align 1
          10:
          11: ; fn_parameters_on_different_lines_debuginfo::foo
          12: ; Function Attrs: nonlazybind uwtable
          13: define i32 `@_ZN42fn_parameters_on_different_lines_debuginfo3foo17ha98e7c29f4ed8d60E(i32,` i32) unnamed_addr #0 !dbg !5 {
          14: start:
          15:  %y = alloca i32, align 4
          16:  %x = alloca i32, align 4
          17:  store i32 %0, i32* %x, align 4
          18:  call void `@llvm.dbg.declare(metadata` i32* %x, metadata !10, metadata !DIExpression()), !dbg !11
          19:  store i32 %1, i32* %y, align 4
          20:  call void `@llvm.dbg.declare(metadata` i32* %y, metadata !12, metadata !DIExpression()), !dbg !11
          21:  %2 = load i32, i32* %x, align 4, !dbg !13
          22:  %3 = load i32, i32* %y, align 4, !dbg !14
          23:  %4 = call { i32, i1 } `@llvm.sadd.with.overflow.i32(i32` %2, i32 %3), !dbg !13
          24:  %5 = extractvalue { i32, i1 } %4, 0, !dbg !13
          25:  %6 = extractvalue { i32, i1 } %4, 1, !dbg !13
          26:  %7 = call i1 `@llvm.expect.i1(i1` %6, i1 false), !dbg !13
          27:  br i1 %7, label %panic, label %bb1, !dbg !13
          28:
          29: bb1: ; preds = %start
          30:  ret i32 %5, !dbg !15
          31:
          32: panic: ; preds = %start
          33: ; call core::panicking::panic
          34:  call void `@_ZN4core9panicking5panic17h2f49f09cf859b728E({` [0 x i64], { [0 x i8]*, i64 }, [0 x i64], { [0 x i8]*, i64 }, [0 x i32], i32, [0 x i32], i32, [0 x i32] }* noalias readonly align 8 dereferenceable(40) bitcast ({ { [0 x i8]*, i64 }, { [0 x i8]*, i64 }, i32, i32 }* `@panic_loc.2` to { [0 x i64], { [0 x i8]*, i64 }, [0 x i64], { [0 x i8]*, i64 }, [0 x i32], i32, [0 x i32], i32, [0 x i32] }*)), !dbg !13
          35:  unreachable, !dbg !13
          36: }
          37:
          38: ; Function Attrs: nounwind readnone speculatable
          39: declare void `@llvm.dbg.declare(metadata,` metadata, metadata) #1
          40:
          41: ; Function Attrs: nounwind readnone speculatable
          42: declare { i32, i1 } `@llvm.sadd.with.overflow.i32(i32,` i32) #1
          43:
          44: ; Function Attrs: nounwind readnone
          45: declare i1 `@llvm.expect.i1(i1,` i1) rust-lang#2
          46:
          47: ; core::panicking::panic
          48: ; Function Attrs: cold noinline noreturn nonlazybind uwtable
          49: declare void `@_ZN4core9panicking5panic17h2f49f09cf859b728E({` [0 x i64], { [0 x i8]*, i64 }, [0 x i64], { [0 x i8]*, i64 }, [0 x i32], i32, [0 x i32], i32, [0 x i32] }* noalias readonly align 8 dereferenceable(40)) unnamed_addr rust-lang#3
          50:
          51: attributes #0 = { nonlazybind uwtable "probe-stack"="__rust_probestack" "target-cpu"="x86-64" }
          52: attributes #1 = { nounwind readnone speculatable }
          53: attributes rust-lang#2 = { nounwind readnone }
          54: attributes rust-lang#3 = { cold noinline noreturn nonlazybind uwtable "probe-stack"="__rust_probestack" "target-cpu"="x86-64" }
          55:
          56: !llvm.module.flags = !{!0, !1}
          57: !llvm.dbg.cu = !{!2}
          58:
          59: !0 = !{i32 2, !"RtLibUseGOT", i32 1}
          60: !1 = !{i32 2, !"Debug Info Version", i32 3}
          61: !2 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !3, producer: "clang LLVM (rustc version 1.39.0 (4560ea7 2019-11-04))", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4)
          62: !3 = !DIFile(filename: "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs", directory: "/home/martin/src/rust")
          63: !4 = !{}
          64: !5 = distinct !DISubprogram(name: "foo", linkageName: "_ZN42fn_parameters_on_different_lines_debuginfo3foo17ha98e7c29f4ed8d60E", scope: !6, file: !3, line: 9, type: !7, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !2, templateParams: !4, retainedNodes: !4)
          65: !6 = !DINamespace(name: "fn_parameters_on_different_lines_debuginfo", scope: null)
          66: !7 = !DISubroutineType(types: !8)
          67: !8 = !{!9, !9, !9}
          68: !9 = !DIBasicType(name: "i32", size: 32, encoding: DW_ATE_signed)
          69: !10 = !DILocalVariable(name: "x", arg: 1, scope: !5, file: !3, line: 1, type: !9)
same:16'0                                              X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
same:16'1                                                                    ?                   possible intended match
          70: !11 = !DILocation(line: 1, scope: !5)
same:16'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          71: !12 = !DILocalVariable(name: "y", arg: 2, scope: !5, file: !3, line: 1, type: !9)
same:16'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          72: !13 = !DILocation(line: 13, column: 2, scope: !5)
same:16'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          73: !14 = !DILocation(line: 13, column: 6, scope: !5)
same:16'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          74: !15 = !DILocation(line: 13, column: 9, scope: !5)
same:16'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>>>
FAIL

With 1.88:
OK
```

<details>

Author: matthiaskrgr

tests/codegen/fn-parameters-on-different-lines-debuginfo.rs

@@ -0,0 +1,18 @@
+//! Make sure that line debuginfo of function parameters are correct even if
+//! they are not on the same line. Regression test for
+// <https://github.com/rust-lang/rust/issues/45010>.
+
+//@ compile-flags: -g -Copt-level=0
+
+#![crate_type = "dylib"]
+#[rustfmt::skip] // Having parameters on different lines is crucial for this test.
+pub fn foo(
+    x: i32,
+    y: i32)
+    -> i32
+{ x + y }
+
+// CHECK: !DILocalVariable(name: "x", arg: 1,
+// CHECK-SAME: line: 10
+// CHECK: !DILocalVariable(name: "y", arg: 2,
+// CHECK-SAME: line: 11